This invention relates to high voltage power supplies and, more particularly, to bushings for connecting external components to components located in a vacuum environment.
High voltage systems frequently must provide for connecting external components to components located in a vacuum environment. A high voltage bushing must provide a continuous electrical path between the two environments and must provide a seal between the two environments over a variety of operating conditions. High voltage bushings are often also filled with a gaseous dielectric, i.e., SF.sub.6, that must be contained and sealed from both vacuum and external environments.
Conventional bushings include a central conductor surrounded by a stacked insulator assembly that contains the dielectric fluid. Any seal between the dielectric fluid and the surrounding vacuum must be able to accommodate circumferential variations in the stacked insulator assembly that arise from stacking tolerances in the component parts of the insulator assembly. Further, a seal must accommodate differential thermal expansion between the central conductor and the surrounding insulator assembly.
Conventional bushings have used a piston-type seal structure where the sealing conductor is a cylinder and seals to an axially-oriented surface on the central conductor. Axial differential movement can then be accommodated between the insulator assembly and the central conductor. Electrical contact between the sealing conductor and central conductor is then generally maintained by a wiping contact, such as flexible conductive fingers extending from the sealing conductor to the central conductor.
The prior art devices use rigid conductors for the sealing conductor and require many parts to form an effective seal while accommodating the variable tolerances in the stacked insulator assembly. Further, the sliding seals are prone to wear and leakage and the sliding electrical contacts are subject to burning and arcing under high current conditions.
These and other problems of the prior art are addressed by the present invention and a flexible conductor assembly provides compression sealing and bolted contact electrical connection between sealing assembly and the central conductor.
Accordingly, it is an object of the present invention to provide only compression seals in a high voltage bushing assembly.
It is another object of the present invention to accommodate component assembly tolerances between sealing surfaces in a central conductor and an insulator assembly in a high voltage bushing while obtaining bolted electrical connections between components.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.